Search results for "Circulation"
showing 10 items of 1137 documents
Pentobarbital-sensitive EDHF comediates ACh-induced arteriolar dilation in the hamster microcirculation
1999
It is unclear to what extent the endothelium-derived hyperpolarizing factor (EDHF) contributes to the control of microcirculatory blood flow in vivo. We analyzed, by intravital microscopy in hamster muscles, the potential role of EDHF along the vascular tree under stimulated (ACh) or basal conditions. Experiments were performed in conscious as well as anesthetized (pentobarbital, urethan) animals. Additionally, cellular effects of the potential EDHF were studied in isolated small arteries. In pentobarbital-anesthetized animals, treatment with N ω-nitro-l-arginine (l-NNA; 30 μmol/l) and indomethacin (3 μmol/l) reduced the dilation in response to 10 μmol/l ACh from 60 ± 6 to 20 ± 4%. This ni…
On the Number of Measurements Necessary to Assess Regional Cerebral Blood Flow by Local Laser Doppler Recordings: A Simulation Study with Data from 4…
1995
Laser Doppler fluxmetry may improve the monitoring of cortical blood flow in neurosurgical patients. So far, however, the variability of laser Doppler readings found in the cerebral cortex has prevented a consequent usage of the technique in clinical practice. The current report analyzes the regional variability of laser Doppler readings from experimental animals. Typical frequency histograms of observed flow values display non-Gaussian distributions. A simulation technique is used to assess the number of measuring sites required for valid estimates of regional cortical flow. From a total of 990 local flow measurements from 45 rabbits random samples of sizes between 5 and 100 were repeatedl…
Patient selection, echocardiographic screening and treatment strategies for interventional tricuspid repair using the edge-to-edge repair technique
2018
Severe tricuspid regurgitation (TR) has long been neglected despite its well-known association with mortality. While surgical mortality rates remain high in isolated tricuspid valve surgery, interventional TR repair is rapidly evolving as an alternative to cardiac surgery in selected patients at high surgical risk. Currently, interventional edge-to-edge repair is the most frequently applied technique for TR repair even though a device has not been developed for this particular indication. Due to the inherent differences in tricuspid and mitral valve anatomy and pathology, percutaneous repair of the tricuspid valve is challenging due to a variety of factors including the complexity and varia…
Effects of severe arterial hypocapnia on regional blood flow regulation, tissuePO2 and metabolism in the brain cortex of cats
1981
The effect of a stepwise decrease in PaCO2 from 3.9-1.6 kPa on rCBF, rCMRO2, tissue PO2 and concentrations of glucose, lactate, pyruvate, ATP, ADP, AMP and phosphocreatine in the brain cortex was studied in cats lightly anaesthetized with sodium pentobarbital. 1. Moderate lowering of PaCO2 to 2.5 kPa induced in all animals a homogeneous decrease of rCBF in corresponding areas of the right and left hemisphere. Mean rCBF fell from 129.2 to 103.1 ml X 100 g-1 X min-1, while rCMRO2 remained unchanged (12.7-12.9 ml X 100 g-1 X min-1). The tissue PO2 frequency histograms showed a shift to lower values without indicating the presence of brain tissue hypoxia. 2. Severe arterial hypocapnia (PaCO2 = …
Rolipram inhibits airway microvascular leakage induced by platelet-activating factor, histamine and bradykinin in guinea-pigs.
1993
Abstract Rolipram (0·1–1000 μg kg−1, i.v.) reduced the increase in microvascular permeability induced by platelet-activating factor (PAF; 50 ng kg−1, i.v.) at different sites of the guinea-pig airways. Rolipram (1–100μg kg−1, i.v.) inhibited histamine (30μg kg−1, i.v.)-and bradykinin (0·3 μg kg, i.v.)-induced airway microvascular leakage. These effects of rolipram were obtained at doses which inhibit histamine (7–20 μg kg−1 min−1)-induced bronchoconstriction (IC50 = 3 ± 1 μg kg, i.v.) without depressing arterial blood pressure in the guinea-pig. Aminophylline (50 mg kg−1) did not change the effect of PAF. The anti-exudative effect of rolipram is of potential therapeutic value in asthma.
Coronary venous therapy to improve microvascular dysfunction.
2021
The coronary circulation is a complex system in which vascular resistances are determined by an interplay of forces in at least three compartments: the epicardial, the microvascular, and the venous district. Cardiologists, and particularly interventional cardiologists, normallly place the focus of their attention on diseases of the epicardial coronary circulation as possible causes of coronary syndromes and neglect the importance of the other two compartments of coronary circulation. The study of the coronary microcirculation, an increasingly recognized source of ischemia, has long been disregarded, but is witnessing a revival since the (re-)introduction of diagnostic tools in the better eq…
Restoration of cerebral and systemic microvascular architecture in APP/PS1 transgenic mice following treatment with Liraglutide™.
2015
OBJECTIVE: Cerebral microvascular impairments occurring in AD may reduce Aβ peptide clearance and impact upon circulatory ultrastructure and function. We hypothesized that microvascular pathologies occur in organs responsible for systemic Aβ peptide clearance in a model of AD and that Liraglutide (Victoza(®)) improves vessel architecture. METHODS: Seven-month-old APP/PS1 and age-matched wild-type mice received once-daily intraperitoneal injections of either Liraglutide or saline (n = 4 per group) for eight weeks. Casts of cerebral, splenic, hepatic, and renal microanatomy were analyzed using SEM. RESULTS: Casts from wild-type mice showed regularly spaced microvasculature with smooth lumenal…
Effect of coronary perfusion rate on the hydrolysis of exogenous and endogenous acetylcholine in the isolated heart
1977
1. The effect of perfusion rate on the hydrolysis of acetylcholine in isolated chicken hearts was studied by measuring both the spontaneous and the evoked output of endogenous acetylcholine into the perfusate in response to vagal stimulation and the arterio-venous difference of exogenous acetylcholine. 2. A decrease in the perfusion rate from 30 to 20 and 10 ml/min caused a graded and significant decline of both the spontaneous overflow of acetylcholine and the overflow evoked by stimulation of both vagus nerves (20 Hz, 1 ms, 40V) for 20 min. The spontaneous and evoked overflow at 30 ml/min were 2 and 3 times, respectively, the overflow at 10 ml/min. 3. Physostigmine (10−6M) raised both the…
Ischemia in patients with no obstructive coronary artery disease: classification, diagnosis and treatment of coronary microvascular dysfunction
2020
Patients with coronary microvascular dysfunction represent a widespread population, and despite the good prognosis, many of them, because of the angina symptoms, have a poor quality of life with strong limitations in their daily activities. In 2017, a new classification of microvascular dysfunction as well as a new definition of ischemia in patients with no obstructive coronary artery disease became available. This new definition improves Kemp's initial work, where cardiac X syndrome was initially described. This work summarizes the last updates on the subject with particular attention to the new classification of microvascular dysfunction, with particular attention to microvascular and vas…
Assessment of pulmonary hypertension by CT and MR imaging.
2003
In the recent World Health Organization (WHO) classification the group of pulmonary arterial hypertension (PH) comprises the classic primary pulmonary hypertension and several conditions with definite or very high risk factors to develop pulmonary arterial hypertension. Therapeutic advances drive the need for a comprehensive pre-therapeutic evaluation for optimal treatment. Furthermore, follow-up examinations need to be performed to monitor changes in disease status and response to therapy. Up to now, the diagnostic imaging work-up of PH comprises mainly echocardiography, invasive right heart catheterization and ventilation/perfusion scintigraphy. Due to technical advances helical computed …